The amount of E. coli bacteria in the water near Science World is nine times what Vancouver Coastal Health deems safe for swimming.
False Creek has long been a no-swimming zone, but the area is a popular paddling spot for residents and tourists.
The health authority is advising people to take extra precautions if they plan to spend time around or on the water.
"Try to avoid ingesting any of the water. After being on the water they should wash their hands prior to eating and they should ideally shower after contact with the water as well," said Randall Ash, General Manager of Environmental Health at VCH.
Water quality advisory signs were put up around False Creek in early July to inform the public of the increased risk, according to Ash.
The signs are important because the appearance of the water does not always reflect how contaminated it is.
Long-time paddler and Vancouver resident Ann Phelps kayaks on False Creek twice a week and says although the water is better than it was 20 years ago, it's still far from being crystal clear.
"It's always had a funny colour," she said.
The presence of E. coli bacteria is an indicator of fecal matter from humans or animals.
A count of 200 parts per 100 ml of water is the recommended threshold for swimming, according to Vancouver Coastal Health.
The most recent measurement for East False Creek is 1961/100ml. Last year, the same area recorded much lower levels, at 492/100ml.Health and city officials say although it is difficult to know exactly what the source of the E. coli is, the hot and dry weather is making the problem worse this year.
"Hot water can speed up bacteria growth in the water. Increased human and animal activity on the beach are also possible causes," said VCH spokesperson Tiffany Akins.
The sunny weather has also attracted more boaters to the area, which can cause higher levels of E. coli, according to the city's director of water sewers and energy Brian Crowe.
"The city is offering free pump out at the civic marinas for boaters to encourage people to behave well if they have toilets in their boats. We are concerned that they may be a significant contributor."
Crowe says the city is working toward making the creek clean enough for swimming.
"False Creek is never considered a swimming area.We'd like it to be one day but we're not there yet."
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